Rotary furnace.



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D. BAKER. ROTARY FURNACE. APPLICATION FILED MAR. 23, 1908. RENEWED JULY 8, 1910. 968,3 1 3. Patented Aug. 23, 1910.

D. BAKER.

- ROTARY FURNACE. APPLICATION FILED MAR. 23, 190B. RENEWED JULY 8, 1910. I 968,31 3. Patented Aug. 23, 1910..

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@Md o I D BAKER ROTARY FURNACE.

APPLICATION FILED 11.53.23, 1908. RENEWED JULY 8, 1910. 968,3 1 3-. Patented Augz'23, 1910.

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UNITED STATES PATENT OFFICE.

DAVID BAKER,

0F PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO LADD & BAKER, INCORPORATED, A CORPORATION OF PENNSYLVANIA.

ROTARY FURNACE.

To all whom it may concern:

Be it known thatv I, DAVID BAKER, of Philadelphia, county of Philadelphia, and State of Pennsylvania, have invented a new and useful Improvement in Rotary Furnaces, of which the following is a specification.

This invention relates to furnaces for roasting or similarly treating materials, such as ores, and is designed for the utilization of the sulfur contained in sulfurous ores, and also for the removal of the sulfur from those ores where the roasting process is the most difficult one, for example, zinc blende, and sulfid and sulfates carrying lead.

The invention relates to improvements in the type of furnace in which the furnace or kiln proper consists of a cylindrical shell supported at a slight inclination downward and rotated on a longitudinal axis, the material to be treated being fed into the upper end of the cylinder and discharged from its lower end, and being subjected in its passage therethrough to an agitating or rolling ac tion due to the rotation of the cylinder, and being subjected also to the influence of a hot blast introduced into the discharge end of the cylinder.

In accordance with the present invention, the rotary shell or furnace proper is formed with a central longitudinal roasting chamber supplied with a hot blast or flame, and a surrounding heating chamber se arate from the roasting chamber and consisting of a number of longitudinally extending heating fines, through which, burning gases are passed during the rotation of the cylinder, the result being that the contents of the roasting chamber may be kept entirely separate from the gases passing through the heating chamber. By this means, I am enabled to recover and utilize the sulfur contained in sulfurous ores. I am enabled also,

by reason of the greater degree of heat to which the roasting chamber may be subjected by the surrounding heating chamber, to remove the sulfur from such ores as zinc blende and sulfids and sulfates carrying lead. I am also enabled in roasting fine ores, to nodulize the same for subsequent use in the blast furnace, the nodulizing effects being secured by raising the temperature in the heating chamber and correspondingly in- Specification of Letters Patent. Patented Aug, 23, 1910, Application filed March 23, 1908, Serial No. 422,730. Renewed July 8, 1910.

Serial No. 571,087.

creasing the temperature in the roasting chamber, to form the maternal therein into a pasty mass, which by the motion of the furnace is formed into balls as usual.

I prefer to employ in connection with a furnace of, this construction, regenerative chambers to heat the blast supplied to the roasting chamber, which regenerative chambers may by the adjustment of suitable valves be connected alternately with the heating fines and with a cold blast supply; whereby the burning gases after their passage through the heating flues are utilized to heat the incoming blast for the roasting chamber.

The invention consists also in the details of construction and combination of parts hereinafter described and claimed.

In the accompanying drawings :Figure 1 is a side elevation of a furnace constructed mend-elevation and partly in transverse section. Fig. 4 is a transverse sectional elevation on the line 44 of Fig. 3. Fig.5 is an end elevation of the rear or lower end of the rotating cylinder showing the nozzles through which the fuel gas is introduced into the combustion chamber, and thence into the heating flues. Fig. 6 is a diagrammatic view showing the circulation through the regenerative chambers of the incoming blast for the roasting chamber and the burning gases from the heating flues.

Referring to the drawings :1 represents a shell or cylinder constituting the furnace or kiln proper which extends at a slight in?- clination downward from the horizontal and which is rotatably supported on rollers 2, a rotary motion being imparted to the cylinder by any suitable mechanism, preferably by means of a drive shaft 3 provided with a driving pinion 4 meshing with a circular rack 5 on the exterior of the cylinder.

At its upper end the interior of the cylinder communicates with a fixed pipe or chamber 6 extending vertically and constituting a gas outlet through which the gaseous products from the combustion in the roasting chamber escape, the ore to be roasted being introduced into the cylinder by means of a downwardly inclined chute 7, extending diagonally through the endof the chamber 6 from the outside and havlng its inner end terminating within the receiving end of the cylinder.

At its opposite end the interior of the cylinder communicates with and is closed by a header 8 terminating at its bottom in a hopper 9, in which the residuum from the 1nterior of the rotary. cylinder is received and from which it may be discharged into cars traveling on a track beneath the hopper.

The cylinder 1 is formed with a central longitudinal passage 10, extending therethrough from end to end, and constituting a roastingchamber, and a number of longitudinally extending surrounding passages 11, constituting heating flues, which flues are separated from each other by radial partitions 11*, and are separated from the roasting chamber by the outer wall 10 of the latter, the roasting chamber and heating flues being thus separate from and independent of each other, for a purpose to be presently described.

In order to resist the elfects of the intense heat to which the walls of the flues and roasting chamber will be subjected, I propose to form the central chamber, the radial partitions and outer walls of the flues of firebrick slabs, the whole being inclosed in a sheet metal sheathing.

At the discharge end of the cylinder, the heating flues communicate with anannular enlarged chamber 12 surrounding the roasting chamber and constituting a combustion chamber, into which is introduced a mixture of fuel-gas and air, which mixture burning in the combustion chamber enters the lower ends of the longitudinal heating flues and passing therethrough, find an exit ,at the opposite ends of the flues, as will be presently described.

In order that the introduction of the fuel gas may take place while the cylinder is rotating, the rear wall of the combustion chamber 12 has formed therein two series of longitudinally extending alining nozzles 13 and 14, forming passageways through said wall, the adjacent ends of the two series of nozzles being separated from each other a slight distance so as to form passages for the entrance of air from air openings 15 into the streams of gas flowing through said nozzles, which gas enters the outer series of nozzles 1a through an annular slit 16 in the front wall of a fixed annular gas chamber 17 formed in the fixed header 8 and supplied with gas by means of a supply pipe leading from any suitable source.

The adjacent walls of the fixed annular gas chamber and the combustion chamber are flat and smooth so as to form when in contact a tight and close joint between the fixed and rotary parts, and in order thatthis contact may be maintained, and the leakage of gas prevented, I propose to so sustain the header 8 that it will be capable of a movement longitudinally to and from the rotating cylinder, and I propose to subject the header to a constant pressure tending to hold .it closely up against said cylinder. As shown in Figs. 1 and 3, this is accomplished by providing longitudinal tracks 18 at the discharge end of the cylinder, on which travel wheels 19, journaled on the sides of the header 8, whereby the header is movable on said tracks to and from the end of the cylinder. The header 8 has attached to it on opposite sides ropes or cables 20 which pass over pulleys 21 mounted on fixed of which cables weights beams 22, to the end 23 are attached and tend to hold the header closely but yieldingly up against the end of the cylinder.

At the opposite end of the cylinder, the roasting chamber is extended longitudinally some distance beyond the ends of the heating flues in the form of a metallic neck 24, which has its end flanged and seated against the flanged end of the gas outlet pipe (3, before alluded to, these two flanged surfaces being in close contact to form a tight joint. Both of these jointsthat between the discharge end of the cylinder and the header 8, and that between the receiving end of the cylinder and the gas outlet pipe t3arc kept cool by means of cooling pipes 25 and 26, the former being embedded in the flanged end of the gas outlet pipe, and the latter surrounding the slit through which the gas flows from the annular gas chamber into the nozzles.

The ends of the heating flues at the receiving end of the cylinder communicate with an annular fixed chamber 27 formed with a front wall 28 and a rear wall 25), the front wall having an opening through which the neck 2+ extends and is rotatably supported, and the rear wall being provided with an opening somewhat greater in diameter and in which the enlarged portion of the cylinder loosely fits, so that it will be free to rotate therein, as a result of which construction the burning gases flowing through the heating flues will enter the said annular chamber 27.

The chamber 27 is connected by means of a flue 30 with two regenerative chambers 30 and 31, extending longitudinally beneath the rotary cylinder and having communication at their opposite ends, by means of branch flues 32 and 33, with a common flue 3% leading to a draft stack 36. A reversing valve 29 controls the flow of the burning gases from chamber 29 to the two regenerative chambers, while a reversing valve 37 controls the communication of the said chambers with the stack.

A blower or air-compressor 40 for supply- I draft stack. blast from the blower flows through the ing the blast for the roasting chamber, communicates by means of a pipe 41 with two branch pipes 42 and 43, connected respectively with the two regenerative chambers, the flow of the air from the blower to said chambers being controlled by a reversing valve 44. At their opposite ends. the two regenerative chambers communicate by means of branch pipes 45 and -16 with a hot blast pipe 47, provided with a reversing valve 48 and connected by means of a sliding joint with a vertical pipe 49, extending horizontally through the rear wall of the header 8, in the form of a horizontal nozzle 50, terminating within the discharge end of the chamber 10, by means of which the hot blast is introduced into said chamber to promote the combustion of the materials therein.

By the proper manipulation of the several reversing valves 29*, 37, 44 and 48, the heating gases from the heating fines may be caused to pass alternately through the regenerative chambers, thereby heating the fire brick, and to flow out through the stack; and the cold blast from the blower may be caused to pass alternately through the two regenerative chambers; whereby it will be heated, whence it will be caused to enter the lower end of the roasting chamber.

In the operation of the furnace, the cylinder has imparted to it a rotary motion, and the ore or other material to be treated is fed by means of chute 7 into the receiving end of the roastingchamber. The rotary motion of the cylinder and its downward inclination cause the ore to travel slowly toward the opposite end, while at the same time being rolled about and agitated, so that every portion of it is subjected to the action of the hot blast which entering the discharge end' of the roasting chamber traverses the latter and escapes with the liberated product gas through the gas outlet pipe 6 at the receiving end of the cylinder. During the roasting action to which the material is thus SllbjGCtQd, the roasting chamber is heated on the outside by means of the streams of burning fuel gas flowing through heating flues 11, the gas entering said flues at the discharge end of thecylinder and leaving them at the opposite end, whence they pass back again toward the discharge end of the cylinder through one of the'regenerative chambers, and finally escape through the At the same time, the cold other regenerative chamber, which had been previously heated by the passage of the fuel gas therethrough, and the air in its passage becomes highly heated by the checker work in the chamber, and in this condition enters the roasting chamber through blast nozale 50 as a. hot blast. The roasted ore flows from the discharge end ofthe roasting chamber and is received in the hopper 9, from which it may be discharged from time to time into suitable receptacles.

It will be observed that the neck 24 of the roast-ing chamber, where it extends within and through the annular fixed chamber 27, is thin, so that the heat from the roasting chamber at this point is radiated through the neck to the gases flowing through said chamber, and in this way an amount of heat is saved, the loss of which would be a considerable item in the roast-ing or noduliz-v ing of fine ores or residues. At the opposite end of the furnace, the radiation of the heat is from the combustion chamber to the roasting chamber, so" that there is a regenerative action of the heat of the combustion gases and the roasting chamber, the incoming hot combustion gases imparting its heat to the roasting chamber at one end, and the burn ing sulfur in the roasting chamber at" the other end imparting its heat to the combustion gases.

Having thus described my invention. what I claim is 1. In a furnace of the type described, a rotary cylindrical furnace properfonmed with a longitudinally extending roasting chamber having an extension at one end and to receive the material to be treated and positioned to effect a gradual movement of such material toward the discharge end of such roasting chamber, a series of longitudinally extending heating fines for the circulation of a heating medium along the external wall-of the roasting chamber and in a direction opposite to the movement of the material, a combustion chamber surrounding the extension of the roasting chamber and with which said fines communicate, and a gas chamber at the opposite end of said cylinder and also with which the tines con1 municate.

2. In a furnace of the type described, the combination with a rotary cylinder formed with a longitudinally extending roasting chamber and surrounding heating fines" and with a hollow extension having its wall of thickness less than that of the wall of the roasting chamber, of means for circulating a heating medium through said flues in one direction, a combustion chamber from which said heating medium is conveyed into said fines and beyond which the roasting chamber extends, and means for introducing the material to be treated into the receiving end I of the roasting chamber, said cylinder being disposed to direct the movement of the material therein in a direction opposite to that of the movement of the heating medium through the fines.

3. In a furnace of the type described, the combination with a rotary cylinder formed with a longitudinally extending roasting chamber and surrounding heating fines and with a hollow extension having its wall of thickness less than that of the wall of the roasting chamber, of means for circulating a heating medium through said fines in one direction. a combustion chamber from which said heating medium is conveyed into said fines and beyond which the roasting chamber extends, means for introducing the ma terial to be treated into the receiving end of the roasting chamber, said cylinder being disposed to direct the movement of the material therein in a direction opposite to that of the movement of the heating medium through the tlues, and means for introducing a hot blast into the opposite end of the roasting chamber and in the direction of movement of the heating medium through the fines.

4. In a furnace of the type described, the combination with a rotary cylindrical furnace-section formed with a longitudinal roasting chamber and with an extension having its wall of less thickness than that of the roasting chamber and with surrounding longitudinal heating fiues,-of an annular combustion chamber with which said fines communicate and from which chamber the burning gases are introduced into the fines, and an annular gas chamber housing the extension of the roasting chamber and from which heat radiates through said extension into the roasting chamber.

5. In a furnace of the type described, the combination with a rotary cylindrical furnace-section formed with a central'longitudinal roasting chamber, surrounding longitudinally extending heating fines, and an annular combustion chamber communicating with said fines, of a fixed annular fuelgas chamber con'nnunicating with the combustion chamber.

6. In a furnace of the type described, the combination with a rotary furnace-section formed with heating fines, an annular combastion chamber communicating with said fines, longitudinally extending nozzles in the wall of the combustion chamber for the introduction of fuel-gas, and a fixed annular gas chamber formed with an annular opening communicating with the nozzles.

7. In a furnace of the type described, the combination with a rotary furnace-section formed with heating fines, and an annular combustion chamber communicating with said fines, of gas entrance openings extending through the wall of the annular chamber and disposed circularly around the longitudinal axis thereof, a fixed annular gas chamber, and an opening through the wall of the chamber extending circularly around the longitudinal axis of the combustion chamber, and communicating with the gas entrance openin s therein.

8. In a furnace of the type described, the combination of a rotary furnace-section provided with longitudinal heating fiucs, and an annular combustion chamber communieating therewith, a" series of longitudinally extending gas entrance nozzles in the wall of the combustion chamber, and air openings in said wall associated with the gas nozzles. 9. In a furnace of the type described, the combination with a rotary cylindrical furnace-section. formed with a central roasting chamber and surrounding heating fiues, of a non-rotatable header closing the end of the roasting chamber and adapted to receive the material discharged therefrom, and an annular gas chamber formed in the header and communicating with the heating fines. 10. In a furnace of the type described, the combination with a rotary cylindrical furnace-section, of a non-rotatable header movable longitudinally to and from the furnace section, and means for maintaining the header yieldingly against the end of the rotary section.

11. In a furnace of the type described, the combination with a rotary furnace-section formed with a roasting chamber and heating fines, and, an annular combustion chamber communicating with said fines, of a nonrotatable header closing the discharge end of the furnace-section and movable to and from the same, an annular gas chamber formed in the header and having a front fiat Wall adapted to cooperate with the rear wall of the combustion chamber to form a tight joint between the parts, said walls being formed with communicating openings; whereby the gas supplied to the gas chamber will enterthe combustion chamber, and means acting on the header and servin to hold the same yieldingly up to the emI of the furnace-section with said cotiperating walls in contact.

12. In a furnace of the type described, the

combination with the rotary cylindrical furnace-section formed with a longitudinal roasting chamber and longitudinally extending surrounding heating fiues, of a fixed annular gas receiving chamber surrounding, and radiating its heat; to the roasting chamber and with which the discharge ends of said fines communicate and a hot-blast member extending into the discharge end of the roasting chamber, whereby a hot-blast may be introduced into said chamber to promote combustion therein.

13 In a furnace of the type described, the combination with a rotary cylindrical furmace-section formed with a central tubular roasting chamber and surrounding longitudinally extending heating fiues, the said tubular chamber being extended beyond the ends of the fines, of a fixed annular chamber formed in one wall with an opening through which the extension of the roasting chamber loosely passes, and having its other wall formed to receive the ends of the heating fiues and a hot-blast member extending into the discharge end of the roasting chamber, whereby a hot-blast may be introduced into said chamber to promote combustion therein.

14. In a furnace of the type described, the combination with a rotary cylindrical furnace-section provided with a roasting chamber and surrounding longitudinally extendin heating flues', of means at one end of the files for supplying the same with fuel-gas, an annular chamber at the opposite end ofthe fines to receive'the gas flowing therethrough, regenerative chambers communicating with said annular chamber, and a reversing valve for controlling said communicatio 15. In a furnace of the type described, the combination with a rotary cylindrical furnace-section provided with a roasting chamber and heating fiues, of means at one end of the fines for supplying the same with fuel-gas, regenerative chambers in communication with the said fines at their opposite ends, a reversing valve controlling said communication, a draft stack communicating with the regenerative chambers, a reversing valve controlling said communication, means for supplying air blast to said regenerative chambers, a reversing valve controlling the said supply, a hot-blast nozz-le entering the discharge end of the roasting chamber, a communication between the nozzle and the regenerative chambers, and and a reversing valve for controlling said cation.

16. In a furnace of the type described, the combination with a downwardly inclined rotary cylindrical furnace-section provided with a central roasting chamber, longitudinally extending surrounding heating flues, and an annular combustion chamhand this tenth of March,

ber at the discharge end of the cylinder communicating with the fines, a non-rotatable hood inclosing the discharge end of the roasting chamber and adapted to receive the residium therefrom, an annular gas chamber formed in said'hood, the said gas chamber and combustion chamber being provided with communicating openings forming a connection between said chambers, means for supplying the annular chamber with fuel-gas, an annular fixed chamber at the opposite end of the cylinder communicating with the heating flues and adapted to receive the burning gases therefrom, a gas outlet at the receiving end of the roasting chamber, and means for introducing the material to be treated into the receiving end of the roasting chamber.

17. In a furnace of the type described, a rotary cylindrical furnace proper formed with a longitudinally extending roasting chamber to receive the materials to be treated and with surrounding heating fines for the circulation of a heating medium and whereby the contents of the roasting chamber are kept separate from the heating medium to facilitate the recovery and utilization of the roduct-gas liberated in the roasting cham ber, said roasting chamber being extended beyond the heating flues and formed by a wall of thickness less than that of the roasting chamber, and a gas chamber surrounding said extending portion of the roasting chamber and from which heat therein contained radiates through said extended portion into the roasting chamber.

In testimony whereof I hereunto set my 1908, in the presence of two attesting witnesses' DAVID BAKER. Witnesses:

C. B. BREWER, Jos. B. ABELE. 

